Among thermoplastic resins, liquid crystalline polymers are known as the materials having excellent dimensional accuracy, damping function, and flowability, and generating very few flash during molding thereof. Due to these advantageous features, the liquid crystalline polymers have been widely adopted as the materials of various kinds of electronic parts.
In particular, connectors in recent years are requested to have increased performance of higher heat resistance (aiming at the increase in productivity by the advanced mounting technology), higher density (multi-pin), and smaller size than ever, accompanied with the increase in performance of electronics devices. By taking advantage of features of the above-mentioned liquid crystalline polymers, liquid crystalline polymer compositions reinforced with glass fiber are adopted as the connectors, (“Full scale survey of Engineering plastics: 1992-1993”, pp. 182-194, (1992), and JP-A9-204951). The planar connector having a lattice structure within the outer frame, represented by CPU socket, shows a significant trend of the increased performance of higher heat resistance, higher density, and smaller size, and thus many kinds of liquid crystalline polymer compositions reinforced with glass fiber are adopted.
However, even the glass-fiber reinforced liquid crystalline polymer compositions having a good flowability to some extent had an unsatisfactory performance for using them as the very thin planar connector having a pitch interval of the lattice part of 2 mm or less and having a width of resin portion of 0.5 mm or less in the lattice area that supports terminals. That is, for a thin planar connector having very small width of the lattice area, in trying to filling the lattice area with resin, the filling pressure increases because of the insufficient flowability, which causes a problem of increased warpage of the obtained planar connector.
To solve the problem, there can be adopted a liquid crystalline polymer having good flowability with decreased amount of glass fiber. That type of composition, however, has poor strength, which then raises a problem of deformation by reflow during mounting.
At present, as described above, there is no planar connector made up of a liquid crystalline polymer, having good performance balance.
Responding to the situations, the inventors of the present invention have proposed a planar connector in JP-A 2005-276758, which planar connector is composed of a specific composite resin composition having a specified relation between the weight average length and the amount of the added fibrous filler.